Operators are beginning to roll out circuit-packet, inter-technology networks where a circuit RAN (Radio Access Network) delivers circuit services support and a packet data RAN delivers packet data services support to a user via ‘dual mode’ mobile station device or a hybrid mobile capable of communicating with both a circuit RAN and a packet data RAN via two access network technologies.
Circuit services support typically includes traditional circuit voice service, Short Message Service (SMS), etc., while packet data services include support for internet applications such as VoIP (Voice over IP), Video Telephony, Instant Messaging, email, etc.
A circuit RAN may include for example a cdma2000 1x RAN as specified by the 3GPP2 A.S00011-A.S00017 Revision C standard specifications. A packet data RAN may include for example an HRPD (High Rate Packet Data) RAN as specified by the 3GPP2 A.S0008-A, A.S0009-A standards specification, and/or some other IEEE 802.x-based packet data network (802.16, e.g.).
FIG. 1 is a block diagram depiction of a wireless communication system 100 in accordance with the prior art. FIG. 1 depicts a circuit-packet, inter-technology network in which the circuit RAN provides circuit voice services support and a packet data RAN such as an HRPD, WiMAX, or other IEEE 802.x-based packet data network provides packet data services to a user of a dual technology mobile. It is assumed here that the circuit network does not support packet data services. Alternatively, the inter-technology network may include two packet data RANs.
FIGS. 2 and 3 are respective block diagram depictions of 3GPP2 A.S0008-B and A.S0009-B inter-technology networks 200 and 300 in which the circuit RAN provides circuit voice service support and the HRPD RAN provides packet data services to a user of a dual mode mobile device. The IWS (Interworking Solution) Function, as specified in A.S0008-B, for example, may be collocated at either the 1x BS or at the HRPD AN, or may exist as a standalone entity. When the IWS function is collocated at the 1x BS, an A21 interface terminates at the 1x BS and the HRPD AN. When the IWS function is collocated at the HRPD AN, an A1/A1p interface is supported by the HRPD RAN and terminates at the MSC and the HRPD AN, and the A21 interface is internal to the HRPD AN. When the IWS exists as a standalone entity, an A1/A1P interface terminates at the MSC and the IWS, and the A21 interface terminates at the IWS and the HRPD AN.
In these types of circuit-packet, inter-technology networks, a dual mode mobile device may be ‘cross-paged’ by the corresponding inter-connected serving RAN, since dual mode mobiles may only be able to monitor incoming signaling from a single air interface at a time. Messages between the circuit RAN and the packet data RAN associated with a mobile device are exchanged over an inter-technology signaling interface (e.g., an A21 connection). For example, air interface messages originating from the circuit RAN are sent by a circuit node in the circuit RAN over the inter-technology interface to a packet data node which is providing packet data services to the mobile in the packet data RAN. U.S. patent application Ser. No. 11/141,926, entitled “METHOD AND APPARATUS TO FACILITATE INTER-OPERABILITY BETWEEN A 3G1X NETWORK AND A WIRELESS PACKET DATA NETWORK,” may be referenced for examples of how a packet RAN may be notified of an incoming circuit voice call from a 1x circuit network. Messages associated with a mobile device operating in the circuit services RAN may also originate in the HRPD RAN and be sent over the inter-technology interface for delivery to the mobile via the circuit services RAN.
Architectures, such as those depicted in FIGS. 2 and 3, may be used to support cross-paging services. For example, when the IWS function is integrated into a 1x BS, or exists as a standalone entity, it receives IOS 1x messages from the MSC via the IOS A1 interface and generates 1x air interface signaling for the mobile which is tunneled over to the HRPD RAN via the A21 interface where the HRPD packet data node (AN/PCF) delivers the 1x message to the hybrid mobile via the CSNA protocol as specified in the 3GPP2-C.S0024-A standard specification.
For example, when the MSC requests the 1x BS/IWS to page the mobile for 1x circuit voice services, the IWS generates a 1x General Page message as specified in 3GPP2 C.S0005-C, tunnels it over the A21 signaling interface to the HRPD AN/PCF. The HRPD AN/PCF delivers the 1x General Page to the mobile via CSNA after which the mobile stops monitoring the HRPD air interface (AIF) forward link signaling and traffic channels and begins exchanging signaling on 1x AIF with the 1x RAN to complete a circuit voice call.
Another example is when the MSC sends an SMS message to the 1x BS for the mobile. The 1x BS/IWS tunnels the SMS message over to the HRPD AN/PCF which delivers the SMS message to the mobile via CSNA allowing the mobile to receive the SMS services while it continues to receive packet data service from the HRPD RAN and without having to return to the 1x RAN to receive the service.
As part of support for the CSNA protocol, C.S0024-A provides the AllowedReverseLinkMessages and AllowedForwardLinkMessages attributes, which the HRPD RAN and mobile use to negotiate and determine which 1x messages in the forward and reverse direction shall be supported. For example, the HRPD RAN and mobile may agree to support the 1x Data Burst message, but not support the 1x General Page message in the AllowedForwardLinkMessages attribute. This information is maintained at the HRPD AN/PCF.
If the HRPD/AN receives a 1x General Page message for the mobile from the IWS, the HRPD AN/PCF should not send the message to the mobile and send a message back to the IWS rejecting the message. Since the IWS/1x RAN is unaware which messages the mobile has agreed to accept, the IWS may continue to send 1x General Page messages (GPM) to the HRPD AN/PCF every time the MSC requests the 1x BS to page the mobile for a circuit voice. The HRPD AN/PCF will continuously reject the message.
The IWS could make an assumption that GPM may not be supported by the mobile (though the mobile may be rejecting the page due to calling party number), and stop sending GPMs for the mobile. However, this assumption could be incorrect if a mobile rejects pages due to the calling party number information, or it just doesn't want to be disturbed with circuit voice services at the time, but is willing to receive them after completing a packet data service (a Video Telephony call, for example).
Furthermore, the HRPD RAN and the MS may renegotiate the AllowedForwardLinkMessages attribute at any time when the mobile is ready to receive a 1x GPM. In this case the mobile will not receive pages since the IWS incorrectly assumed that the message is not supported and is no longer forwarding GPM messages for the mobile to the HRPD RAN.
FIG. 4 is a signaling flow diagram that depicts present-day signaling example for a situation in which 1x General Page messages (GPMs) are not supported, in accordance with the prior art. A detailed description of the signaling flow timeline as labeled on the rightmost column of FIG. 4 follows:                401. The mobile HRPD PD NODE negotiates (or renegotiates) which 1x forward link messages shall be supported via the HRPD CSNA AllowedForwardLinkMessages attribute. In this scenario, GPM messages will not be supported.        402. A circuit voice call arrives for the mobile at the 1x RAN. The MSC sends an A1 page message to the IWS (or 1x BS/IWS).        403. The IWS sends an A21 1x Air Interface message containing a 1x General Page message to the HRPD PD NODE where the mobile is receiving packet data service.        404. The HRPD PD NODE responds with an A21-Ack message rejecting the message since the mobile notified the HRPD PD NODE that 1x GPMs via CSNA should not be sent to it.        405. The IWS sends an A1 Rejection message to the mobile to notify the MSC that the mobile rejected the 1x circuit voice call.        406. Another circuit voice call arrives for the mobile at the 1x RAN. The MSC sends an A1 page message to the IWS (or 1x BS/IWS).        407. The IWS sends another A21 1x Air Interface message containing a 1x General Page message to the HRPD PD NODE where the mobile is receiving packet data service.        408. The HRPD NODE responds with an A21-Ack message rejecting the message since the mobile notified the HRPD PD NODE that it should not be sent 1x GPMs via CSNA.        409. The IWS sends an A1 Rejection message to the mobile to notify the MSC that the mobile rejected the 1x circuit voice call.        
This process may continue repeating and result in excessive signaling resource wastage over the A21 interface. Thus, it would be desirable to have a method and apparatus that could provide better interworking in an inter-technology network to avoid certain signaling inefficiencies.
Specific embodiments of the present invention are disclosed below with reference to FIGS. 5-7. Both the description and the illustrations have been drafted with the intent to enhance understanding. For example, the dimensions of some of the figure elements may be exaggerated relative to other elements, and well-known elements that are beneficial or even necessary to a commercially successful implementation may not be depicted so that a less obstructed and a more clear presentation of embodiments may be achieved. In addition, although the signaling flow diagrams above are described and shown with reference to specific signaling exchanged in a specific order, some of the signaling may be omitted or some of the signaling may be combined, sub-divided, or reordered without departing from the scope of the claims. Thus, unless specifically indicated, the order and grouping of the signaling depicted is not a limitation of other embodiments that may lie within the scope of the claims.
Simplicity and clarity in both illustration and description are sought to effectively enable a person of skill in the art to make, use, and best practice the present invention in view of what is already known in the art. One of skill in the art will appreciate that various modifications and changes may be made to the specific embodiments described below without departing from the spirit and scope of the present invention. Thus, the specification and drawings are to be regarded as illustrative and exemplary rather than restrictive or all-encompassing, and all such modifications to the specific embodiments described below are intended to be included within the scope of the present invention.